Liquid level control apparatus



United States Patent Otice 3,170,479 Patented Feb. 23, y1965 l 3,170,479LIQUID LEVEL CONTROL APPARATUS Richard J. Mueller, Franklin Park, Ill.,assignor to Automatic Canteen Company of America, Chicago, Ill., acorporation of Delaware Continuation of application Ser. No. 802,365,Mar. 27, 1959. This application Jan. 17, 1962, Ser. No. 168,574 Claims.(Cl. 137-392) This invention is a continuation of my copendingapplication, Serial Number 802,365, filed on March 27, 1959, nowabandoned, and relates to control apparatus and, more specifically, toapparatus which is particularly well adapted for automaticallycontrolling the liquid level in coin operated beverage vending machines,and the like.

It is a primary object of the present invention to provide novel controlapparatus which is operable in a novel and expeditious manner toautomatically control the liquid level in tanks, or the like.

Another object is to afford novel control apparatus which is operable ina novel and expeditious manner to automatically feed a suitable chargeof liquid into a tank, or the like, when the liquid level in the tankfalls below a predetermined level.

Another object is to insure, in a novel manner, that not more than thedesired chargeof liquid is discharged into such a tank.

A further object is to provide novel electrically operated controlapparatus which is operable to continually sense the liquid level in atank, or the like, in a novel and expeditious manner.

Another object is to provide novel control apparatus of theaforementioned type which is continually operable but which at mosttimes in normal operation draws little power and a minimum current.

Yet another object of the .present invention is to provide novel controlapparatus of .the aforementioned type which embodies parts affording aresonant circuit and sensing devices constituted and arranged in a noveland expeditious manner so as to afford an effective control foroperation of a valve.

A further object of the present invention is to afford novelelectrically operable control apparatus of the aforementioned type whichis practical, reliable, efficient and economical in operation; iscompact in size; may be `quickly and easily serviced and maintained; andmay be readily and economically produced commercially.

Another object is to afford novel electrically operated controlapparatus of the aforementioned type which may be readily installed in arelatively limited space in coin operated beverage vending machines suchas, for example, coffee vending machines, and the like, to afford anovel and practical liquid control therefor.

` Another object of .the present invention is to afford a novelelectrically operated control apparatus of the aforementioned typewherein, if the electric power from the electric power supply source isinterrupted, or is interrupted and then reestablished, the machineautomatically l resumes normal operation when the power is reestablishedand an undesired cycle of operation such as, for example,

the feeding of an undesired charge ofv liquid is not effected.

Other and further objects of the present invention will be apparent fromthevfollowing description and claims and are illustrated in theaccompanying drawings which, by way of illustration, show the preferredembodiments of the present invention and the principles thereof, andwhat I now consider to be the best mode in which I have contemplatedapplying these principles. Other embodiments of .the invention embodyingthe same or equivalent principlesr may be used and structural changesmay be made as desred by those skilled in the art without departing fromthe present invention and the purview of the appended claims.

In the drawings:

FIG. l is a 4partially schematic and partially sectional View of controlapparatus embodying the principles of my invention; and

FIG. 2 is a view similar to FIG. l, but showing a modified form of myinvention.

In FIG. l, control apparatus, embodying the principles of my invention,is shown to illustrate the preferred embodiment of my invention.

The control apparatus is shown in FIG. l in position to control thelevel of liquid in a suitable container 1, such as, for example, thebeverage storage tank in a suitable coffee vending machine, or the like.The control apparatus includes an isolation transformer 2 having itsprimary connected to a suitable source of electrical power such as, forexample, power 'lines 3 and 4 of a suitable power source such as, `forexample, a volt, 60 cycle power source. One side of the secondary of thetransformer 2 is connected by a suitable conductor 5 to ground, and theother side of the secondary of the transformer 2 is connected by asuitable conductor 6 to one side of a capacitor 7. The other side of thecapacitor 7 is connected by a suitable conductor 8 to one side of thecoil 9 of a relay 10, and the other side of the coil 9 is connected by asuitable conductor 11 to ground.

A normally closed switch 12 and a normally open switch 13 are soassociated with the relay 10 that when the coil 9 is deenergized or isnot excited with full exciting current, the switch 12 is closed andtheswitch 13 is open, and when the coil 9 is energized with full excitingcurrent, the relay 10 is effective to open the switch 12 and close theswitch 13 and to hold the same in these latter respective positions. Theswitches 12 and 13 may be spring biased or otherwise urged toward theirnormal positions; viz., switch 12 closed and switch 13 opened.

One side of the switch 12 is connected by a suitable conductor 14 to theconductor 8. The conductor 14 is also connected by a suitable conductor15 to the upper end of an electrode 16 mounted in a suitable supportingmember such as the cover member 17 mounted on the open upper end of theytank 1. The supporting member 17 may be made of any suitable dielectricmaterial such as, for example, rubber, or the like, to thereby afford anelectrically insulated support yfor the electrode 16 on the tank l.

The side of the switch 12 opposite to the side connected to theconductor 14 is connected by a suitable conductor 18 to anotherelongated electrode 19 supported by the cover member 17 in electricallyinsulated relation to the tank 1. Both of the electrodes 16 and 19 areso supported by the cover member 17 that they extend downwardly into thetank 1 in spaced relation to each other, and in spaced relation to thewalls of the tank 1. As may be seen in FIG. 1, the electrode 19 extendsdownwardly into the tank 1 a considerably greater distance than does theelectrode 16, for a purpose whichwill be discussed in greater detailpresently.

One side of the normally open' switch 13 is connected by a suitableconductor 20 to the power line 3, and the other side ofthe switch 13 isconnected by a suitable conductor 21 to one side of the coil 22 of anelectrically operated valve 23. The other side of thecoil 22 isconnected by a suitable conductor 24 to the other power line 4, so thatwhen the switch 13 is closed, the coil 22 is energized to thereby openthe valve 23. The valve 23 may be any one of a number of suitableelectrically operated valves readily available on the market and isdisposed between an inlet conduit 25 and an outlet conduit26 for "j ,o fcontrolling that flow of liquid from the conduit 25 to the conduit 26.The conduit 2S may be connected to a suitable source of liquid, notshown, which it is desired to p feed into the tank 1 in controlledamounts in the operation of my novel apparatus. The conduit 26 extendsfrom the valve 23 into position whereby when liquid flows from the valve23 through the conduit 25 it is discharged thereby through an opening Z7in the cover 17 into the tank 1.

In the normal operation of the control apparatus shown in FIG. 1, thetank 1 is initially filled with the liquid to be dispensed therefromsuch as, for example, the aforementioned coffee, to a level 2S whereinthe lower end of the electrode 1o is just in contact with the uppersurface of the liquid in the tank 1. lt will be seen that under suchconditions, and with the switch 12 ciosed, two parallel shunt circuitsare alfored around the coil 9. One of the shunt circuits extends fromthe conductor 8 through the conductor 14, the switch 12, the conductor1&the electrode 19, the liquid in the container 1, and a conductor 29,which may include the container 1, to ground. The other shut circuitextends from the conductor t5 through the conductors 14 and 15, theelectrode 1d, the liquid in the container 1, and the conductor 29 toground.

The impedance of the capacitor 7 and the coil 9 are substantially thesame at the frequency of Yelectric power source to which they are to beconnected, and are so selected that the series circuit which l haveafforded across the secondary of the transformer 2, and which includesthe capacitor 7 and the coil 9, is a resonant circuit when theaforementioned shunt circuits through the electrodes 16 and 19,respectively, are open. Thus, for example, l have found that when mynovel control apparatus is used in a coffee beverage vending machinevwherein the liquid in the tank 1 is coffee, and wherein the transformeris such as to afford a secondary voltage of 135 volts at 60 cycles,

a suitable resonant circuit may be afforded with the capacitor 7 beingone-half microfarad condenser and the coil 9 being a two thousand ohmresistance coil.

When the series circuit through the capacitor '7 and the coil 9 is aresonant circuit, the current flow through the coil 9 is sufficient tofully excite the latter. However, the impedance of each of the shuntcircuits through the electrodes 16 and 19, respectively, when eachrespective circuit is closed, is substantially less than the impedanceof the coil 9 so that,'when either of the aforementioned shunt circuitsis closed the coil 9 is shorted out so that the series circuit throughthe capacitor 7 and the coil 9 is out of resonance and the current flowthrough the coil 9 is insufficient to fully excite the coil 9 and,therefore, the relay 1t) is ineffective to either open or close theswitches 12 and 13, respectively, or to hold them opened or closed,respectively.

Thus, when the tank 1 is filled to the normal initial level, wherein theliquid is in Contact with both of the electrodes 16 and 19, the coil 9is shorted out through both of the aforementioned shunt circuits. Thisis true because, with the liquid in the tank 1 in contact with theelectrode 16 the coil 9 is shorted out so that the current flowtherethrough is less than necessary to excite the coil 9 sufficiently toopen the switch 12 or to hold it open and, therefore, the latter isclosed so that the shunt circuit through the electrode 19 is alsoclosed.

As liquid is withdrawnfrom the tank 1, the level thereof falls below thelevel 2f and, therefore, the liquid moves out of Contact with theelectrode 16 while still remaining in contact with the electrode 19.Hence, while the one shunt Vcircuit is stili maintained from thecapacitor 7 through the switch 12 and the electrode 19 to ground, theother shunt circuit from the capacitor 7 through the electrode 16 isbroken.

As the removal of liquid from the tank 1 continues, the liquid level inthe tank 1 continues to drop toward the level Sti, at which it is justin contact with the electrode 19. During this drop, the coil 9 remainsshorted through the electrode 19 and, therefore, the relay 1t) remainsineffective to close the switch 13 or to open the switch 12. Whensulhcient liquid has been withdrawn from the tank 1 that the liquidfalls below the level Sil so that the liquid is no longer in contactwith the electrode 19, the short circuit of the coil 9 is completelybroken, and sufficient current then flows through the coil 9 to fullyexcite the latter and thereby cause energization of the relay 1t)effective to open the switch 12 and close the switch 13.

The closing of the switch 13 is effective to energize the coil 22 of thevalve 23 to thereby cause the valve 23 to be opened and feed liquid fromthe conduit 2.5 through the conduit 26 into the tank 1. As the liquidagain rises in the tank 1 it first reaches the level 35B where it againcontacts the lower end ofthe electrode 19. However, it will beremembered that the switch 12 hasv been opened by energization of therelay 1t) and, therefore, the circuit between the electrode 19 and thecapacitor 7 is broken. Hence, the relay 1t) is maintained in energizedcondition by the current flow through the coil 9.

As the liquid thereafter continues to rise in the tank 1, it eventuallyagain reaches the level 28 wherein it is in contact with the lower endportion of the electrode 16. This again. affords a short circuit for thecoil 9, the circuit extending from the secondary of the transformer 2hrough the capacitor 7, the conductors 8, 14 and 15, the electrode 1o,the liquid in the tank 1, the conductor 29, and ground back to thesecondary of the transformer 2. Upon this deenergization of the relay11B, the switch 13 again opens to thereby deenergize the coil 22 andclose the valve 23, and shut olf the flow of liquid from the supplyconduit 2S through the conduit 26 into the tank 1. The deenergization ofthe relay 11i is yalso effective to permit the switch 12 to again closeand rwhereby reestablish the circuit rom the secondary of thetransformer 2 through the electrode 19 and back through ground to thesecondary of the transformer 2. When this occurs, the control apparatusis ready for another complete cycle of operation.

It will be seen that with my novel control apparatus as shown in FIG. 1,the only current flow therethrough is normally that through thetransformer 2, the switch 13 being normally open so that ymost of thetime no current flows through the circuit which includes the switch 13and the coil 22. When the circuit through the capacitor 7 and the coil 9is out of resonance, very little current flow through the transformeroccurs, all the circuits across the secondary of the transformer at suchtime being in series with the capacitor 7 and out of resonance. The

onlyitime that substantial current flow occurs through the controlapparatus is during a refilling operation, when the switch 13 is closedand the circuit through the capacitor 7 and the coil 9 lis in resonance.`Hence, it will be seen that my control apparatus is capable ofcontinuous automatic functioning with relatively little power beingdrawn.

In FIG. 2, a modilied form of my novel control apparatus illustrated inFG. 1 is shown, and the parts of the apparatus shown in FTG. 2 which arethe same as parts of the apparatus shown in FIG. 1, are indicated by thesame reference numerals. l

`ill-fence, it will be seen that in the apparatus shown in FIG. 2, theprimary of the transformer 2 is connected to power lines 3 and 4; thesecondary of the transformer 2 is connected by a conductor 6, acapacitor 7, and conductors S and 145, to one side of a normally closedswitch 12; and the otherV side of the switch 12 is connected by'` )l aconductor 18 to an electrode 19 mounted on the tank/'1 kin electricallyinsulated relation thereto by means/bf a bodied in the apparatus showninFIG. 1.

valve 23, and a conductor 24'to the power line 4. The valve 23 is theapparatus shown in FIG. 2, like the valve 23 shown in FIG. l, isconnected to a suitable supply Yconduit 25 and a discharge conduit 26and is effective, `when open, to feed liquid from the conduit 25 throughthe conduit 26 into the opening 27 in thecover mernber 17.

The control apparatus shown in FIG.-2y also includes the relay effectiveto control the opening and closing of the switches 12 and 13 aspreviously described, the coil 9 of the relay 10 lbeing connected at oneside to the conductor 8 and at theother side by a conductor 11 to groundas in the control apparatus shown in FIG. 1.

The primary difference between the control apparatus shown in FIG. l andthat shown in FIG. 2 is that the apparatus shown in FIG. 2 does notembody the shunt circuit which includes the electrode 16, and some partsembodied in the apparatus shown in FIG. 2 are not em- These additionalparts embodied in the apparatus shown in FIG. 2

include a synchronous timer 31 for limiting the quantity of liquid fedinto the tank 1 in any one refilling cycle. The timer 31 embodies amotor 32 which is connected in parallel to the coil 22 of the valve 23between the conductors 21 and 24, a conductor 33 connecting one side ofi the motor 32 to the conductor 21, and a conductor 34 connecting theother side of the motor 32 to the conductor 24.

Also, one side of a normally open switch 35 is connected by a conductor36 to the conductor 8, and the other side of the switch 35 is connectedby a suitable conductor k37 to ground. The motor 32 is drivinglyconnected to a suitable cam 38 which is effective at the close of eachrotation of the latter to momentarily close the normally open switch 35.

In the operation of the control apparatus shown in FIG. 2, the tank 1 isalso normally initially filled to the level 28. This means that theelectrode 19 is disposed in the liquid and, therefore, the coil 9 of therelay 10 is short circuited by the circuit which includes the normallyclosed switch 12 and the electrode 19. As liquid is Withdrawn from thetank 1, this short-circuited condition of the coil 9 prevails untileventually the liquid in the tank 1 drops below the level 30 and,therefore, out of contact with the electrode 19. When this occurs,

CTI

the short circuit around the relay 10 is broken to thereby 4through thedischarge conduit 26 into the tank 1. The

closure of the switch 13 in the apparatus shown in FIG. 2 is alsoeffective to close the circuit from the power line 3 through theconductor 20, the switch 13, the conductors 21 and 33, the motor 32, theconductor 34, and the conductor 24, to the power line4 4 and therebyenergize the motor 32. Operation of the motor 32 is effective to rotatethe cam 38 in a clockwise direction as viewed in FIG. 2 from its initialposition as shown in FIG. 2. Toward the close of a complete rotation ofthe cam 38, the

, lobe 39 thereon moves into engagement with the switch Y35 andmomentarily closes the same. When this occurs,

it will be seen that a short circuit around the relay 10 is againestablished from the conductor 8 through the conductor 36, the switch35, and the rconductor 37 back through ground to the open side of thesecondary of the transformer 2. This, it will be seen, is yeffective todeenergize the relay 10 to again cause the switch 13 to open and therebyclose the valve 23 and shut off the flow of liquid through the conduit26 into the tank. The opening of the switch 13 is also effective todcenergize the motor 32, the overrun of the motor 32 being sufficient tocarry the cam 38 past switch-closing relation to switch 35 and back toinitial starting position.

The deenergization ofthe relay 10, caused by the aforementioned closingof the switch 35, is also effective to cause the switch 12 to close.Ifthe amount of liquid fed into the tank 1 during the precedingliquid-feeding cycle has been insufficient to raise the liquid in thetank toa level wherein it is again in contact with the electrode 19, theshort circuit through the electrode 19 remains broken. Therefore, undersuch circumstances, as soon as theswitch 35 is permitted to open bythepassage of the cam lobe 39 out of switch-closing engagement therewith,the coil 9 is immediately energized to initiate another completeliquid-feeding cycle of operation. However,

if at the end of a liquid-feeding cycle of operation the' liquid in thetank is again in contact with the electrode 19, the closing of theswitch 12,*caused by the momentary shorting out of the coil 9 throughthe switch 35 at the close of the cycle of operation, is effective toreestablish the shunt circuit from the conductor 8 through the electrode19 and the liquid in the tank 1 back through ground to the other side ofthe secondary of the transformer 2 and thereby short out the coil 9 ofthe relay 10 until sufficient liquid has again been withdrawn from thetank 1 to uncover the electrode 19.

It will be seen that with the apparatus shown in FIG. 2, only apredetermined amount of liquid is fed into the tank 1 during a cycle ofoperation of the synchronous timer 31. This is true even though duringthe refilling operation additional liquid should be withdrawn from thetank 1, the lobe 39 on the cam 38 causing the switch 35 to be closedafter one cycle of operation to thereby again deenergize the relay 10.Hence, it will be seen that this is one basic difference between thecontrol apparatus shown in FIG. 2 and that shown in FIG. 1, the controlapparatus shown in FIG. 1 being effective to continuously feed liquidinto the tank 1 until the liquidagain reaches its initial level 28,where it again contacts the lower end of the electrode `115. However,both forms of my novel apparatus are effective to automatically andeffectively keep a tank or other suitable container filled with liquidto a desired level, even though liquid may be withdrawn from the tankduring the refilling operation, it being understood, of course, thatunder such conditions the feeding of liquid into the tank during arefilling operation is greater than any withdrawal of liquid from thetank during the refilling operation.

It will be seen that when using either of the forms of my novel controlapparatus shown herein to control the liquid `level in a suitablecontainer such as, for example, the tank 1, there is no danger that aninput power failure to the control apparatus will cause an undesiredopening of the valve 23 with a consequent undesired feeding of a charge,or a partial charge of liquid into the tank 1. Thus, it will be seenthat in my novel control apparatus the switch 12 is normallyclosed kanda power failure to the relay 10 does not effect any actuation of thevalve 23 or of the synchronous timer 3l, and vthat even after such aninterruption, the reestablishment of power to the control apparatus doesnot effect any such undesired operation of the valve 23 or the timer 31,the circuit through the switch 12 remaining effective to short circuitthe relay 10.

This, it will be seen, is important when the control apparatus is to beused in devices or machines wherein it is desirable that flooding or thesurreptitious withdrawal of liquid is tobe prevented. Thus, for example,it will be seen that if the level of the liquid in the tank 1 was atsuch a height that an additional charge of liquid into the tank 1 wouldcause an overflow therefrom, flooding of the device or apparatus couldresult from a power failure to the transformer 2 if the apparatus wereso constructed that interruption or reestablishment of energization fromthe power source were effective to cause an additional feeding of liquidinto the tank. Also, in machines such as certain types of beveragevending maandava chines wherein filling of the supply tank to a levelabove a ypredetermined level is effective to discharge beverage from theusual discharge nozzle, surreptitious removal of such beverage could beeffected by unplugging the machine from its power source and againplugging it into the power source if such actions were effective tocause a liquid-feeding cycle of operation whereby liquid was fed intothe supply tank. My novel apparatus protects against such'accidentalflooding, or surreptitious Withdrawal of liquid or beverage, from such atank.

From the foregoing it will be seen that l have afforded a novel andpractical control apparatus which is effective, efficient and reliablein controlling the liquid level in a container such as a tank, or thelike. Also, it will be seen that I have afforded a novel control Yapparatus which may be incorporated in compact form in relatively smallspaces.

In addition, it will be seen that I have afforded a novel and practicalcontrol apparatus which may be readily and economically producedcommercially.

Thus, while I have illustrated and described the preferred embodimentsof my invention, it is to be understood that these are capable ofvariation and modification, and I therefore do not Wish to be limited tothe precise details set forth, but desire to avail myself of suchchanges and alterations as fall within the purview of the followingclaims. v

' I claim:

1. ln a iiuid control apparatus of the type comprising a fluidcontaining container, valve means operable to feed fluid into saidcontainer, and means for sensing the fluid level within said containerincluding at least one electrode adapted to normally be in contact witha portion o f the fluid contained within said container, the improvementtherein comprising, in combination, a confined quantity of electricallyconductive fiuid, first switch means for controlling the operation ofsaid valve means, a transformer, a capacitor connected to one side ofthe secondary of said transformer, a relay including a coil, firstcircuit means including said coil connecting said capacitor in seriesback through ground to the other side of said secondary, other circuitmeans connected to said first circuit means between said coil and saidcapacitor for short circuiting said relay, said other circuit meansincluding a normally closed switch and said confined fluid, said relaybeing operative to close said first switch and open said `second switchwhen the iiuid present reaches a level suiiicient to interrupt thecurrent in said other circuit means, said relay being renderedinoperative to hold said first switch closed and said second switch openwhen the fluid level being sensed reaches a level sufficient to restoresaid other circuit to current carrying capacity.

2. In a fluid control apparatus of the type comprising a iiuidcontaining container, valve means operable to replenish fluid confinedin said container, and means for sensing the level of the confinedfluid, the level-responsive means comprising in combination, normallyopen electrical circuit means connected to said Valve means forcontrolling operation of the latter, a relay normally energized belowfull exciting current, said relay being operable when energized withfull exciting current to close said normally open circuit means, atransformer, a capacitor having substantially the same impedance as saidrelay, second circuit means including said capacitor and relay connectedin series across the secondary of said transformer with one side of saidcapacitor connected to one side of said secondary and one side of saidrelay connected through ground to the other side of said secondary,third circuit means including a normally closed switch adapted and saidrelay having impedances of such a nature that when said third circuitmeans is open, said second circuit means affords a series resonantcircuit effective to energize said relayywith full exciting current, andwhen said third circuit means is closed, said second circuit means isout of resonance and is ineffective to energize said relay with fullexciting current.

3. Control apparatus for monitoring and restoring the liquid level in acontainer which comprises electrical connection means adapted to beconnected to a fluctuating potential electric power source, an isolationtransformer having its primary connected across said connection means,series resonant circuit means, including a capacitor and electromagneticmeans, connected across the secondary of said transformer with one endof said circuit means connected directly to one side of said secondary,with said capacitor connected between said side and said electromagneticmeans, and the Vother end of said circuit means connected through groundto the other side of said secondary, said capacitor and electromagneticmeans having substantially the same impedance, two electrodes, means forsupporting said electrodes in electrically insulated relation tol eachother with one of said electrodes extending downwardly farther than theother of said electrodes, second series circuit means of lesserelectrical impedance than said electromagnetic means and including anormally closed switch and said one electrode, said second circuit meansbeing connected in series with said capacitor across said secondary frombetween said capacitor and said electromagnetic means when said switchis closed and the liquid present is at a level above the bottom of saidone electrode, with one side of said second circuit means connecteddirectly to said series resonant circuit means and the other side ofsaid second circuit means, including said liquid, connected throughground to said other side of said secondary, third series circuit meansof lesser electrical impedance than said electromagnetic means includingsaid other electrode, said third circuit means being connected in serieswith said capacitor across said secondary from between said capacitorand said electromagnetic means when said liquid in said container is ata level above the bottom of said other electrode, with one sidev of saidthird circuit means connected directly to said series resonant circuitmeans and the other side of said third circuit means, including saidliquid, connected through ground to said other side of said secondary,means, including a valve, for selectively replenishing the confinedliquid, and fourth circuit means, including a normally open switch,connected to said connection means and operable upon closing of saidnormally open switch to effect opening of said valve to replenish saidliquid, said fourth` circuit means being operable upon opening of saidnormally open switch to effect closing of said valve and therebyterminate feeding of liquid, said electromagnetic means being operativeto open said normally closed switch and close said normally open switchwhen said second and third circuit means are open and being ineffectiveto open said normally closed switch or to close said normally openswitch when either said second or third circuit means are closed.

4. A fluid level control apparatus, adapted for use with a container ofelectrical conducting fluid, comprising: valve means operable to feedfluid into said container, and means for sensing the fluid level withinthe container;

said sensing means including first switch means for conf trolling theoperation of said valve means, second switch means for controlling theactivation of at least one portion of said sensing means, fluid levelresponsive means for to be in series with at least a portion of saidsensing means and operable to connect said second circuit means to Yground from between said capacitor and said relay, said relay beingoperable when energized with full exciting 4current to open saidnormally closed switch, said capacitor closing said first switch meansand opening said i'second switch means in response to a predeterminedfluid level in the container to thereby operate said valve means to addfluid to said container and to deactivate said one portion of saidsensing means, and means for shunting out said level responsive meansthrough the fluid in the container when a predetermined fluid level hasbeen attained to thereby open said first switch means andrender saidvalve means inoperative and to close said second switch means forreactivating said one portion of said sensing means. y

5. A uid level control apparatus for use with a container ofelectrically conductive fluid, comprising: valve meansA operable to feedfluid into said container; and means for sensing the level of said uidincluding, electrode means having at least one electrode normally incontact with the fluid, first switch means for controlling the operationof said valve means, second switch means for controlling theenergization of said electrode means, electromagnetic means responsiveto a loss of contact between the uid in said container and said oneelectrode for closing said first switch means to operate said valvemeans to feed fluid to said container, and opening said second switchmeans to de-energize said one electrode;

References Cited by the Examiner UNITED STATES PATENTS 1,346,898 7/20Kingsbury 137-392 2,357,371 9/44 Wolfner S17-123.4 2,539,206 10/48Robinson 317-141 2,588,677 3/52 Welty et al 137-391 2,766,406 10/56Schwarzkopf 317-132 WILLIAM F. ODEA, Primary Examiner.

M. CARY NELSON, Examiner.

5. A FLUID LEVEL CONTROL APPARATUS FOR USE WITH A CONTAINER OFELECTRICALLY CONDUCTIVE FLUID, COMPRISING: VALVE MEANS OPERABLE TO FEEDFLUID INTO SAID CONTAINER; AND MEANS FOR SENSING THE LEVEL OF SAID FLUIDINCLUDING, ELECTRODE MEANS HAVING AT LEAST ONE ELECTRODE NORMALLY INCONTACT WITH THE FLUID, FIRST SWITHCH MEANS FOR CONTROLLING THEOPERATION OF SAID VALVE MEANS, SECOND SWITCH MEANS FOR CONTROLLING THEENERGIZATION OF SAID ELECTRODE MEANS, ELECTROMAGNETIC MEANS RESPONSIVETO A LOSS OF CONTACT BETWEEN THE FLUID IN SAID CONTAINER AND SAID ONEELECTRODE MEANS, FOR CLOSING SAID FIRST SWITCH MEANS TO OPERATE SAIDVALVE MEANS TO FEED FLUID TO SAID CONTAINER, AND OPENING SAID SECONDSWITCH MEANS TO DE-ENERGIZE SAID ONE ELECTRODE; AND MEANS FOR SHUNTINGOUT SAID ELECTROMAGNETIC MEANS WHEN THE LEVEL OF FLUID IN THE CONTAINERRISES TO A PREDETERMINED LEVEL FOR THEREUPON OPENING SAID FIRST SWITCHMEANS SAID SECOND SWITCH MEANS.